1. Field of the Invention
The present invention relates in general to vehicle passive restraint systems of the type typically known as airbags. In particular, the present invention relates to an improved arrangement for attaching an inflatable cushion to an inflator.
2. Description of the Related Art
Airbag passive restraint systems generally include a crash sensor, an inflator, and a Cushion. The crash sensor determines when the airbag system should be activated, and sends an appropriate signal to the inflator. Upon receipt of the signal, the inflator expels a quantity of gas. This gas is received within the cushion, causing it to inflate to protect the passenger.
A common problem in airbag system design has been the attachment of the cushion to the inflator. This is because the gas is expelled from the inflator with a large velocity in order to inflate the cushion within the short amount of time available (on the order of 10 ms). This high velocity gas creates a force in the cushion tending to blow the cushion from the inflator.
The connection between the cushion and the inflator must of course be strong to retain the cushion, but should also be simple to assemble and inexpensive to produce. Various arrangements have been employed to connect the cushion to the inflator. Many of these are rather complex, and require a great deal of assembly time. One of the more simple arrangements is disclosed in U.S. Pat. No. 5,259,641 to Schenk et al. In the Schenk et al. patent, the mouth or inlet opening of the cushion is placed upon one side of a mounting plate, while the inflator is placed against the other side of the mounting plate. A rigid reinforcing ring is then placed over the mouth of the cushion, to hold the mouth between the ring and the mounting plate. The fasteners which hold the inflator to the mounting plate also hold the ring, and thus the cushion, to the plate.
While this arrangement provides a secure mounting for the cushion, it is still sufficiently complex that it increases the time required to assemble the airbag system, and increases its cost. In particular, the use of the separate mounting ring requires that it be fabricated from metal, that it be manually inserted into the cushion, and that the fastener process is only visible from one side.